Key words : Hematopoietic stem cell transplantation, Pretransplant, Rhinosinusitis, Sinusitis, Solid-organ transplantation

Introduction

A higher number of transplant candidates and medical and surgical advancements have led to an increased number of transplants performed over the past decades. Solid-organ transplant (SOT) recipients receive chronic immunosuppressive medication to prevent organ rejection after transplant. In hematologic patients, heavy immunosuppressive treatment is administrated before allogenic hematopoietic stem cell transplant (HSCT) to prevent graft rejection or graft-versus-host disease. Afterward, a gradual recovery of the immune system is obtained over the first 2 years. After autologous HSCT, continued oral immunosup-pressives are given for the first 6 months to 1 year (or even longer). Chronic immunosuppression can aggravate latent infections, leading to potentially severe and life-threatening infections. An unde-restimated problem is the development of rhinosinusitis, as clinical signs can be masked in the immunosuppressed host but can evolve into fulminant disease progression.1 Immunosuppressed transplant recipients may struggle to control the infection, leading to much higher rates of morbidity, hospitalization, costs, transplant failure, and even mortality.^2,3 In addition, organ transplant recipients are more likely to experience a more serious and advanced illness course.⁴

With an increasing number of both HSCT and SOT performed and the improvement in life expectancy of transplant recipients, the prevalence of these transplant-related ear-nose-throat (ENT) conditions is increasing, with an additional 3 per 10 000 transplant patients needing surgical ENT care annually.⁴ During the pretransplant work-up, an increasing number of patients are therefore referred to otolaryngology departments to exclude latent infectious or (pre)malignant processes. Indeed, ENT problems seem to be among the most common findings at the pretransplant consultation.^4,5 The practice of a pretransplant ENT evaluation is heterogenous among hospitals worldwide and displays the need for a clear and uniformly accepted protocol. However, a standardized ENT evaluation has not been recommended in most recent transplant guidelines (except for liver transplant guidelines), and there is no internationally accepted protocol available concerning the evaluation and management of ENT complications in these patients. As such, we have conducted a systematic review of available evidence regarding the pretransplant sinonasal evaluation and provide an evidence-based screening protocol.

Materials and Methods

Study selection
Articles were searched through PubMed, Scopus, and Google Scholar until July 2023, using the terms “pretransplant,” “immunocompromised,” “solid organ transplantation” or “hematopoietic/bone marrow/stem cell transplantation,” “otolaryngology,” “paranasal sinus,” and “sinusitis” and the medical subject heading terms “Organ transplantation,” “Stem cell transplantation,” “Otolaryngology,” “Paranasal sinuses,” and “Sinusitis.” We selected articles first by title and abstract, with final selections made after reading the full text. We included only articles in English. The search was performed independently by CDV and CB, based on Preferred Reporting Items of Systematic Review and Meta-Analysis (PRISMA) guidelines (Figure 1).

We included those articles that described para-nasal manifestations in the peritransplant period (SOT and autologous or allogenic HSCT). We excluded articles that described only invasive fungal rhinosinusitis cases, mostly nontransplant patients, or lung transplant recipients with rhinosinusitis (because chronic rhinosinusitis with and without polyposis is nearly a universal finding in cystic fibrosis patients). We also excluded articles analyzing the same population, studies that were included in other meta-analysis, and case reports or smaller case series (5 cases or less).

Quality and statistical analyses
Quality analysis with bias assessment and summary of evidence was performed on outcome level, using the Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) system (Figure 2).⁶ We extracted data on study design, population characteristics, type of transplant, pre- and posttransplant prevalence rates, overall mortality rates, and diagnostic approach. Rhinosinusitis was diagnosed according to the diagnostic criteria used in the included articles. We calculated prevalence and mortality rates from available data if necessary. We performed a meta-analysis on studies that reported pretransplant rhinosinusitis prevalence or overall survival rates. We converted relative risk (RR) to natural log-transformed formats to deal with skewness. We evaluated heterogeneity by Cochran Q and quantified by the I2 statistic. If the value of I2 was >50% and the Q-test yielded P < .10, heterogeneity was considered statistically significant. Whenever considerable heterogeneity was expected, we performed sensitivity analyses to determine the source of heterogeneity by excluding 1 study at a time. The random effects model was applied to estimate the pooled prevalence and 95% CI. We analyzed differences between prevalence and mortality rates according to type of transplant with the independent samples Kruskal-Wallis-test, with P < .05 by 2-sided tests determined to be significant. We assessed publication bias through visual inspection of the funnel plot of log-RR and Egger test of all-cause mortality. We performed statistical analyses with IBM SPSS Statistics for Windows, version 29 (IBM Corp). Experts in the field of transplant medicine and otolaryngology revised recommendations and the final protocol.

Results

A systematic search of literature resulted in 29 articles, with 27 retrospective observational studies on rhinosinusitis in transplant recipients (9 SOT, 18 HSCT) and 2 review articles on HSCT. None of the included studies were randomized controlled trials. Two systematic reviews on rhinosinusitis after HSCT were excluded from meta-analysis.⁷ Regarding patient selection, some studies only included symptomatic patients with already presumed sinusitis before transplant. Selection bias probably explains the higher prevalence of rhinosinusitis found in these studies, with were also excluded from meta-analysis.^8-12 Study design and characteristics are displayed in Table 1 and Table 2.^{1-3,8-11,13-31}

Prevalence of pretransplant rhinosinusitis
Of the 22 studies eligible for meta-analysis, 4 studies did not report pretransplant prevalence rates.3,8,20,26,29 Most studies did not distinguish between acute bacterial, chronic, or fungal rhinosinusitis. The average prevalence of pretransplant rhinosinusitis was 6.1% (95% CI, 3.0-9.3). Ortiz and colleagues did not observe any case with rhinosinusitis.23 Patients undergoing SOT (7 studies) had preexisting rhinosinusitis in 3.9% (range, 1.3%-18%), whereas a prevalence of 22.2% (range, 0-61.3%) was detected before HSCT (11 studies). A relative risk (RR) of 4.9 (95% CI, 4.2-5.6) was found comparing HSCT with SOT pretransplant prevalence, which was significantly higher (P < .05) (Figure 3). In the general population, a 1-year prevalence of acute rhinosinusitis of 7% to 15% was described.32 Pooled analysis was heterogeneous (I2 = 100%), as expected in prevalence estimates because of differences in population and geographical characteristics and diagnostic criteria. Heterogeneity did not resolve after further sensitivity analyses, even when 2 the outliers were excluded; therefore, the random-effects meta-analysis model was employed. The prevalence of posttransplant rhinosinusitis has not been analyzed, due to missing values (mostly not reported in SOT studies) and high risk of bias (differences in posttransplant screening and sinusitis treatment regimens).

Overall mortality
Only 6 of the included studies actively investigated overall survival outcome in transplant recipients with rhinosinusitis. Almost no data were available on disease-specific survival outcomes. After we pooled 426 patients with pretransplant sinusitis and 729 patients without sinusitis, overall (not disease specific) mortality rates were similar in transplant recipients with and without rhinosinusitis (mean 23.9% vs 29.1%, RR 0.82; Figure 2). The calculated log-transformed RR of mortality rates in patients with pretransplant rhinosinusitis is illustrated for each study in Figure 4. As shown, only Kishimoto and colleagues reported a significantly elevated mortality rate in HSCT patients with rhinosinusitis compared with patients without sinusitis.² Again, pooled analysis of data was heterogeneous (I2 = 51%), indicating important differences in mortality rates in the included studies; heterogeneity did not resolve after further sensitivity analyses, so the random-effects model was employed.
However, overall mortality was higher in pretransplant patients with rhinosinusitis after HSCT versus after SOT. When these subgroups were compared, the overall mortality rate in patients with pretransplant rhinosinusitis was significantly higher after HSCT (mean 50.4%) compared with SOT (mean 14.6%) (RR 2.8; 95% CI, 2.1-3.9; P < .05). However, mortality was not disease-specific and was influenced by numerous confounding variables (see Discussion).

Pandrangi and colleagues retrospectively studied 7069 transplant patients, who mostly had HSCT, and reported overall in-hospital mortality in 229 patients (3.2%).³ The authors also found no statistically significant difference in transplant-related mortality between patients with rhinosinusitis and patients without sinusitis. They did not report on overall survival rates. Surgery did not seem to significantly improve survival outcomes of patients with rhinosinusitis.³ In contrast, Kishimoto and colleagues found that pretransplant sinus disease had a profound effect on the clinical outcomes of HSCT. Patients with preexisting sinonasal disease had a significantly lower overall survival 2 years after transplant (42% vs 64%, respectively; P = .012) and a significantly higher transplant-related mortality than in patients without sinusitis (48% vs 17%; P = .008).² This mortality seems to increase significantly if graft-versus-host disease is present.³³ Importantly, a significantly higher cumulative incidence of respiratory failure and pulmonary complications were seen in the rhinosinusitis group, which could provide a possible explanation of worse outcome in this group.²

Previous studies have indeed indicated the relationship between upper and lower respiratory disease.³² This is consistent with the findings of Billings and colleagues,²¹ who found that patients with severe pretransplant sinus disease tend to have poorer overall 2-year survival outcomes than those with mild or moderate rhinosinusitis. Mortality after 2 years reached 78% of those with severe rhinosinusitis, compared with 57.1% with mild changes and 40% with moderate changes on their computed tomography (CT) scans. However, findings were not statistically significant (P = .750), and mortality was not disease specific in any patient but was mainly linked to sepsis or pulmonary complications.²¹ Importantly, both Kishimoto and colleagues and Billings and colleagues performed studies on children, indicating a possible higher risk of mortality in younger transplant patients with rhinosinusitis.^2,21

Sekine and colleagues described that the resolution of rhinosinusitis after HSCT was significantly correlated with decreased mortality (83.3% reduction; P = .003), with an increased mortality in allogenic compared with autologous stem cell transplant.¹² The authors argued that a higher Lund-Mackay score cannot be correlated with increased mortality, as the degree of opacification is unlikely to be important in this context. Other radiological signs, such as bone destruction, complete opacification, invasion of soft tissue structures, are more likely to be of clinical importance.¹²

Regarding survival data of SOT recipients with rhinosinusitis, a comparative analysis on liver transplant patients by Hong and colleagues revealed a higher overall mortality rate in those who did not receive a pretransplant sinonasal evaluation than in patients who did; however, the significantly higher Model for End-Stage Liver Disease (MELD) score of the first group indicated severe comorbidity and could be responsible for the higher mortality rate, along with other infectious causes such as pneumonia.¹⁴ The authors also found that patients with pretransplant rhinosinusitis who were treated had significantly lower mortality than those who did not receive treatment, with no differences in Lund-Mackay or MELD score. There was however no significant difference in overall mortality in patients with abnormal and normal pretransplant CT sinus.¹⁴ Yel and colleagues found no significant differences in overall survival and infectious complications up to 1 year after liver transplant when acute or chronic rhinosinusitis was present at pretransplant evaluation or after transplant; they also found no significant difference in MELD score.¹⁷ Moon and colleagues did not report lethal infectious complications in 2 patients who died after liver transplant.¹³

Discussion

Infections greatly contribute to transplant-related morbidity and mortality, mainly because of chronic immunosuppression in transplant recipients. A thorough screening of preexisting infectious condi-tions is therefore recommended prior to transplant.5 Rhinosinusitis is an underestimated cause of potentially severe and life-threatening infections.^1,2 Moreover, the clinical presentation of rhinosinusitis may be subtle in the immunocompromised host, but the subsequent clinical course can be fulminant.¹ The disease may be difficult to treat in immunosup-pressed or transplant patients and is responsible for significantly increased morbidity, hospital stay, costs, transplant failure, and even mortality according to some studies.^2,3 In this regard, we performed a meta-analysis of rhinosinusitis prevalence and overall mortality rates in transplant recipients. Our systematic review could not detect a significantly higher overall mortality in transplant recipients with pretransplant rhinosinusitis. Routine pretransplant screening of rhinosinusitis could therefore be regarded as unnecessary in asymptomatic patients. However, the study demonstrated a higher prevalence and higher odds of overall mortality after HSCT compared with SOT. Also, immunosup-pression can exacerbate latent infections and mask symptoms. These findings emphasize a possible benefit of sinonasal screening before transplant to reduce complications after transplant, especially in the HSCT population. However, such evaluation is mostly not specifically recommended in current international transplant guidelines due to hete-rogeneity in data (except for liver transplant guidelines).

Prevalence of rhinosinusitis in transplant recipients
First and most importantly, it was usually not indicated what proportion of patients had acute bacterial, chronic, or invasive fungal rhinosinusitis. The lack of distinction among these entities prevents true meaningful interpretation of the results of the included studies. Moreover, the prevalence of pretransplant rhinosinusitis varies with the type of transplant (SOT vs HSCT), diagnostic criteria used, studied population, or transplanted organ. Higher prevalence rates are also influenced by an increased number of screenings performed, raising prevalence rates in hospitals with high-quality screening regimens. Before SOT, the prevalence of pretransplant rhinosinusitis seems comparable to the reported 7% to 15% one-year prevalence of the general population.³² Patients with a hematologic malignancy or primary immunodeficiency are at a higher risk of opportunistic infections because of immunosuppressive therapy used after allogeneic HSCT and prolonged leukopenia/neutropenia after allogeneic and auto-logous HSCT.^27,34 The prevalence of preexisting rhinosinusitis is therefore higher in HSCT than in SOT and is more present in allogenic than in autologous stem cell transplant.^19,25,28 This was also demonst-rated by our findings. Other conditions such as end-stage renal and hepatic disease with impaired immunity can also affect the prevalence of pretransplant rhinosinusitis.¹⁸ Importantly, lung transplant recipients were excluded because most of these patients are cystic fibrosis patients with concurrent chronic rhinosinusitis. This would artificially increase the prevalence in SOT recipients. However, all lung transplant patients especially require ENT evaluation for rhinosinusitis symptoms.

The prevalence or development of posttransplant rhinosinusitis could not be analyzed because this number is largely dependent on utilized treatment regimens, diagnostic approach, and the grade of immunosuppression after transplant. The reported prevalence rates are therefore less likely to be representative. Usually, posttransplant CT scans were only used when there was a clinical suspicion of rhinosinusitis, raising the prevalence rates of posttransplant rhinosinusitis in some studies. Luckily, only a small proportion (0.5% to 4%) of these patients had acute invasive fungal rhinosinusitis; however, mortality can be high (50%-90%).^20,21,27,31 Concerning chronic rhinosinusitis, there seems to be no alterations in incidence or clinical course after transplant, probably because immunosuppressive treatment suppresses the inflammatory pathways; however, evidence is lacking.^8,11,15,16

Overall, most authors did not detect a significant correlation between pre- and posttransplant rhinosinusitis. Comparing prevalence rates between the included studies is hampered by several different factors. As many of the included studies are older studies, most studies were performed before publications of the European Position Paper on Rhinosinusitis and Nasal Polyps guideline (EPOS), and different types of diagnostic approaches were used.³² Importantly, some authors diagnosed rhino-sinusitis only by radiologic abnormalities.^2,8,21,24,30 Moreover, not all patients included in the studies had a routine pretransplant CT paranasal sinus scan. Finally, because the included studies reported different types and transplanted organs, different immunosuppressive regimens were used.

Mortality rates in transplant recipients with rhinosinusitis
Our findings suggest that there is no increased risk of overall mortality in transplant recipients with rhinosinusitis compared with those without, neither in the SOT group nor after HSCT. Length of follow-up was unfortunately not always indicated in the included studies. However, overall mortality was significantly higher after HSCT patients with rhinosinusitis (mean 50.4%) compared with SOT with rhinosinusitis (mean 14.6%), with a RR of 2.8 when mortality rates of rhinosinusitis patients in those 2 subgroups were compared. Importantly, mortality rates were not disease specific and are intrinsically higher after HSCT. It is likely that the higher reported overall mortality rates after HSCT were caused by factors other than rhinosinusitis, such as graft-versus-host disease, other serious infections (pneumonia, sepsis, endocarditis), or other comorbidities. It is also important to repeat that no distinction among acute bacterial, chronic, or fungal rhinosinusitis was made.

Pretransplant clinical examination
During symptomatic evaluation, patient medical history and signs should be questioned, such as nasal blockage, obstruction, congestion, discharge (anterior/posterior nasal drip), facial pain or pressure, and reduction of smell and cough, as indicated by current EPOS guidelines.³² Fever lasting more than 2 days under adequate antibiotic treatment in a neutropenic patient should be alarming and could possibly indicate a severe or invasive infectious cause.³⁴ However, it is important to consider that symptoms could be reduced by immunosuppressive treatment or immunodeficiency.⁸

Because pathological CT findings appear in both asymptomatic and symptomatic patients, nasal endoscopy remains an essential part of the examination, especially in symptomatic patients.³² Clinical sinonasal examination with nasendoscopy should evaluate possible signs of mucosal edema, discharge, obstruction, or nasal polyposis.³² Mucosal discoloration, severe edema, necrosis, decreased sensation to pain, or absence of bleeding should raise suspicion of invasive fungal rhinosinusitis.^32,34 Of the included studies, many studies (but not all) routinely performed pretransplant nasal endoscopy in evaluating sinus disease in each transplant recipient.^{1,11,15,16,18,27,31,33} Endoscopic grading was not standardized, with only a few studies using the Lund-Kennedy score. In other studies, nasal endoscopy was not routinely performed or mentioned. Importantly, endoscopic findings may be more subtle in immuno-suppressive patients, and pretransplant endoscopic evaluation is not able to predict the occurrence of posttransplant rhinosinusitis.²⁷ A thorough evaluation of the patient’s history and clinical examination with nasal endoscopy could avoid routine paranasal sinus CT scan in asymptomatic pretransplant patients for exclusion of rhinosinusitis.^11,32

Screening with paranasal sinus computed tomography
The utility of pretransplant screening with routine paranasal sinus CT scan remains a subject of controversy. In healthy asymptomatic patients, an abnormal CT sinus is found in 30% to 40%, which increases the likelihood of false positives during screening.^2,11,32 However, because symptoms and clinical signs may be reduced due to immunosup-pression, many authors have recommended a thorough evaluation with additional imaging, where screening with plain radiographic scan is outdated because CT imaging is far more sensitive.³² The interpretation of the acquired imaging plays an important role as well. Although some of the included studies defined rhinosinusitis solely based on radiologic abnormalities, discrete mucosal swelling on CT scans is not diagnostic for rhinosinusitis in transplant or nontransplant patients.^11,32 Moreover, in transplant patients, immunosuppression not only reduces symptoms but also radiographic abnorma-lities such as mucosal thickening or air-fluid levels.^8,12,30

Although immunosuppression attenuates clinical and radiological signs, there still seems to be a good correlation between symptoms and radiologic abnormalities according to studies in immuno-compromised children after HSCT.^8,21,30 In contrast, severe radiographic rhinosinusitis before transplant is associated with more severe symptoms after transplant in children, increasing the need for pretransplant sinonasal screening in younger transplant recipients.²¹ For asymptomatic children, one should be careful with routine CT imaging, as the risk of radiation-induced malignancy is higher, especially if it is unlikely to result in alterations in therapy.²⁴ According to Leite and colleagues, magnetic resonance imaging could be a reliable alternative.¹⁰

The role of pretransplant sinonasal evaluation is to prevent systemic bacterial or fungal infections after immunosuppression. Fungal rhinosinusitis is a specific entity that has the potential to become a severe invasive infection in the immunocom-promised host. However, because fungal balls are usually asymptomatic and nasal endoscopy findings are unlikely to show any abnormalities, additional evaluation with imaging may be necessary to detect these cases. However, it is impossible to predict which patients will eventually develop invasive fungal rhinosinusitis after transplant based on clinical or radiological data.^15,31 In a study by Harreld and colleagues invasive fungal rhinosinusitis was found in 2% of patients after HSCT, but no patient had clinical or imaging findings suspicious of fungal infection before transplant.³¹ Moreover, it seems unlikely that a severe invasive infection could develop without accompanied symptoms, even in immunocompromised patients.^8,21,30,31 This would argue against routine imaging for the detection of fungal balls in transplant recipients. Given the rarity of invasive fungal rhinosinusitis in transplant recipients, guidelines are extrapolated from data on immunosup-pressed patients. The authors suggested treating latent fungal infections in pretransplant patients, to possibly prevent severe invasive infection afterward. In case of invasive fungal rhinosinusitis in immunosuppressed patients, the transplant and ENT specialists should be urgently consulted. Reduction of immunosuppression should be discussed, and urgent aggressive surgical debridement with antifungal medical therapy should be promptly administrated.^32,35

Overall, studies on the utility of CT screening of rhinosinusitis in transplant patients are hard to compare, due to the heterogenicity in study protocols. Some articles (mostly HSCT-related) advised pretransplant sinus CT evaluation based on the higher reported incidences of rhinosinusitis or mortality rates.^1,2,21,23,24 Other authors could not indicate any significant benefit of routine radiologic screening. In kidney transplant recipients, for example, the prevalence of pretransplant acute rhinosinusitis is found to be low, and the prevalence and recurrence rate of rhinosinusitis do not increase after transplant.¹⁸ Therefore, routine sinonasal evaluation for asymptomatic patients before SOT was not recommended by the authors, considering the cost and time involved.^14,16,18 Additionally, evidence lacks on when to perform a pretransplant sinus evaluation, as not all studies indicated the timeframe of screening before transplant.

Treatment
The treatment of rhinosinusitis and the necessity to perform surgery depends on several patient and disease-related factors that are largely independent from transplant and are beyond the scope of this article. Currently, there are no clear guidelines on the optimal management of patients with rhinosinusitis during the pretransplant or posttransplant period, especially with respect to sinus surgery.⁷ Because of the heterogenicity in the included studies, no conclusions could be made regarding the potential decreased risk of posttransplant rhinosinusitis in treatment of pretransplant patients. Overall, a surgical approach is reserved for patients who do not respond to medication or have a fungal ball or acute or chronic invasive fungal rhinosinusitis, to prevent invasive infection in the immunocompromised host.¹⁸ When in doubt, it is however safer to assume that transplant patients have rhinosinusitis and introduce appropriate medical or surgical treatment than to ignore this possibility and allow a possibly fatal local or generalized spread of infection.⁷

Protocol
Based on the above-described available data in literature, we have proposed a protocol for pretransplant ENT investigations (Figure 5). The protocol is comparable to Mirza and colleagues and Ghazizadeh and colleagues.^36,37 Mirza and colleagues proposed a sinonasal screening and treatment protocol for immunocompromised patients and only advised imaging in symptomatic patients, which differs from our study, as we advocate routine pretransplant sinus CT in all adult HSCT patients. More recently, Ghazizadeh and colleagues published a similar review on HSCT patients.³⁷ They dif-ferentiated the need for pretransplant sinus CT based on fungal, chronic, or acute rhinosinusitis in HSCT recipients and proposed an algorithmic flow chart, which was largely based on common clinical practice. Our findings mostly agree with the proposed clinical screening protocol. However, they did not advocate routine pretransplant CT sinus in asymptomatic HSCT recipients, whereby latent fungal rhinosinusitis could be missed.

Strengths and limitations
To our knowledge, this is the first systematic review in this domain that performed a meta-analysis of available data and directly compared rhinosinusitis in HSCT versus SOT patients. Risk of bias and heterogeneity was assessed. Egger test and funnel plot analysis did not suggest risk for publication bias. Two other reviews on rhinosinusitis in HSCT recipients have been published^7,37; however, these did not report any risk of bias and did not assess SOT patients. Mirza and colleagues also proposed a similar screening protocol, but the authors mainly focused on acute fungal rhinosinusitis.³⁶

Our study had various limitations. The protocol and recommendations were based on almost solemnly retrospective observational studies, with low quality of evidence and high risk of bias due to patient selection. Another limitation was the relatively small sample size of the included studies, increasing the likelihood of a type II error. Comparison between studies with provision of a coherent conclusion was hampered due to various confounding variables, inconsistency in findings, diagnostic criteria, treatment protocols, study design, and outcome measures. Rhinosinusitis was mostly not further subdivided in acute bacterial, chronic, or fungal rhinosinusitis in the included studies, which further impeded the interpretation of results. In addition, the observed high heterogeneity in the pooled analysis was another limitation that could hinder the generalizability of our findings. As length of follow-up was not always indicated, incidence rates could not be calculated, and mortality rates were prone to confounding. The reported overall mortality rate was an indirect outcome measure of pretransplant rhinosinusitis and was therefore less likely to be important in developing pretransplant screening guidelines; however, disease-specific data were mostly not available in the included studies.

Conclusions

There are no generally accepted guidelines on practical ENT evaluations in transplant recipients. We performed a systematic review with meta-analysis of sinonasal assessments in transplant recipients. We could not detect a significantly higher overall mortality rate in transplant recipients with pretransplant rhinosinusitis. However, we found a significantly higher prevalence of pretransplant rhinosinusitis in HSCT patients. Endoscopic asses-sment should be performed in all transplant recipients, in line with its availability and low cost. Routine radiological screening with paranasal sinus CT usually does not seem necessary in asymptomatic patients before SOT, as prevalence and mortality rates are relatively low, unless there is clinical suspicion of underlying infection. However, because rhinosinusitis is more prevalent and HSCT recipients are more prone to severe infections, a routine pretransplant evaluation with CT of the paranasal sinuses is advocated in this group. Importantly, pretransplant rhinosinusitis does not seem to predict the posttransplant outcome, as most included studies did not provide any relationship between pretransplant rhinosinusitis and disease severity after transplant.

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